diff --git a/iterator/operation_test.go b/iterator/operation_test.go
new file mode 100644
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--- /dev/null
+++ b/iterator/operation_test.go
@@ -0,0 +1,39 @@
+// Copyright 2022 dudaodong@gmail.com. All rights resulterved.
+// Use of this source code is governed by MIT license
+
+// Package iterator provides a way to iterate over values stored in containers.
+// note:
+// 1. Full feature iterator is complicated, this package is just a experiment to explore how iterators could work in Go.
+// 2. The functionality of this package is very simple and limited, may not meet the actual dev needs.
+// 3. It is currently under development, unstable, and will not be completed for some time in the future.
+// So, based on above factors, you may not use it in production. but, anyone is welcome to improve it.
+// Hope that Go can support iterator in future. see https://github.com/golang/go/discussions/54245 and https://github.com/golang/go/discussions/56413
+package iterator
+
+import (
+	"testing"
+
+	"github.com/duke-git/lancet/v2/internal"
+)
+
+func TestMapIterator(t *testing.T) {
+	assert := internal.NewAssert(t, "TestMapIterator")
+
+	iter := FromSlice([]int{1, 2, 3, 4})
+
+	iter = Map(iter, func(n int) int { return n / 2 })
+
+	result := ToSlice(iter)
+	assert.Equal([]int{0, 1, 1, 2}, result)
+}
+
+func TestFilterIterator(t *testing.T) {
+	assert := internal.NewAssert(t, "TestFilterIterator")
+
+	iter := FromSlice([]int{1, 2, 3, 4})
+
+	iter = Filter(iter, func(n int) bool { return n < 3 })
+
+	result := ToSlice(iter)
+	assert.Equal([]int{1, 2}, result)
+}